Pollution control in wood products dryer operation

Abstract

Problems associated with deposition of contaminants from air streams in transport ducts in the wood products industry and other sources of such contaminants are at least minimized by close coupling a cyclone separator/scrubber to the source of the air stream.

1. A method of removing gas-borne contaminants transported from an operation producing gas-borne contaminants by a duct to a contaminant removal operation, wherein the duct is prone to build up of contaminants deposited from the gas stream, the improvement which comprises eliminating the duct and wherein the operation producing gas-borne contaminants comprises a wood products dryer operation wherein moist wood chips, sawdust, wood fiber or other wood products or biomass are dried in a dryer using a hot air stream and dried wood products are transported in the air stream to a cyclone separator where the wood products are separated from the air stream and collected for processing into saleable products. 
     
     
       2. The apparatus of  claim 1  wherein the contaminant removal operation includes a combined cyclone separator, contaminant scrubber and air stream quencher. 
     
     
       3. The apparatus of  claim 2  wherein said contaminant removal operation further includes a wet electrostatic precipitator. 
     
     
       4. The apparatus of  claim 3  wherein said contaminant removal operation further includes a thermal oxidizer system and/or biofilter. 
     
     
       5. The apparatus of  claim 4  wherein the thermal oxidizer system is a thermal catalytic oxidizer, regenerative thermal oxidizer or regenerative catalytic oxidizer. 
     
     
       6. The apparatus of  claim 1  wherein a portion of the air stream is recycled. 
     
     
       7. The apparatus of  claim 1  wherein the operation producing gas-borne contaminants is a panel board manufacturing operation wherein wood particles are formed into panel board using thermosetting adhesive and gaseous by-products are vented. 
     
     
       8. In an apparatus for removing gas-borne contaminants transported from an operation producing such gas-bome contaminants by a duct to a contaminant removal operation, wherein the duct is prone to build up of contaminants deposited from the gas stream, the improvement which comprises eliminating the duct and wherein the operation producing gas-borne contaminants comprises a wood products dryer operation wherein moist wood chips, sawdust, wood fiber or other wood products or biomass are dried in a dryer using a hot air stream and dried wood products are transported in the air stream to a cyclone separator where the wood products are separated from the air stream and collected for processing into saleable products. 
     
     
       9. The apparatus of  claim 8  wherein the contaminant removal operation includes a combined cyclone separator, contaminant scrubber and air stream quencher. 
     
     
       10. The apparatus of  claim 9  wherein said contaminant removal operation further includes a wet electrostatic precipitator. 
     
     
       11. The apparatus of  claim 10  wherein said contaminant removal operation further includes a thermal oxidizer system and/or biofilter. 
     
     
       12. The apparatus of  claim 11  wherein the thermal oxidizer system is a thermal catalytic oxidizer, regenerative thermal oxidizer or regenerative catalytic oxidizer. 
     
     
       13. The apparatus of  claim 8  wherein a portion of the air stream is recycled. 
     
     
       14. The apparatus of  claim 8  wherein the operation producing gas-borne contaminants is a panel board manufacturing operation wherein wood particles are formed into panel board using thermosetting adhesive and gaseous by-products are vented.